Truncated reelin protein and DNA encoding the same

ABSTRACT

The present invention provides a truncated Reelin protein containing a F-spondin domain and a CR-50 recognition site but containing no repeat site of a Reelin protein, and a DNA encoding the truncated Reelin protein. The truncated Reelin protein and the DNA encoding this protein of the present invention can be utilized for treatment of diseases including agyria due to abnormal alignment of neurons.

FIELD OF THE INVENTION

[0001] The present invention relates to a truncated isoform of a Reelin protein and a DNA encoding the truncated Reelin protein.

BACKGROUND OF THE INVENTION

[0002] Neuroblasts born on the cerebral ventricle side migrate to their destinations following this developmental fate and achieve their final differentiation in the developmental stages of the central nerve system. The question is how neuroblasts recognize their destinations. Reeler mice have been long known as mutant mice which are very useful in studying this mechanism. In Reeler mutant mice, neuroblasts cannot migrate to their correct destinations, so that abnormal alignment of neuroblasts are found in various locations in the central nerve system including cerebrum, cerebellum, and hippocampus.

[0003] To identify a molecule deficient in a Reeler mutant mouse, we immunized a Reeler mutant mouse with a normal embryonic mouse brain, obtaining a monoclonal antibody CR-50 (Neuron 14, 899-912, 1995). Therefore, localized expression of CR-50 antigens in Cajal Retzius cells was found in cerebrum.

[0004] Then, a Reelin protein which is a causative gene of the Reeler mutant was cloned (Nature 374, 719-723, 1995, Genomics 26, 543-549, 1995, Nature Genetics 10, 77-82, 1995).

[0005] A Reelin protein is a huge extracellular protein, comprising a F-spondin domain having a certain degree of homology with F-spondin on its N-terminal side, and of eight Reelin repeats occupying the most of Reelin protein on its C-terminal side beyond the hinge region (Nature 374, 719-723, 1995). Each Reelin repeat contains an EGF-like motif so that Reelin protein is predicted to have features of extracellular matrix (ECM).

[0006] In addition, it was shown that a CR-50 antigen is a Reelin protein itself and can also inhibit the function of Reelin both in vitro and in vivo (J. Neurosci., 17, 23-31, 1997; Nature 385, 70-74, 1997; J. Neurosci., 17, 3599-3609, 1997; Proc. Natul. Acad. Sci. USA, 94, 8196-8201, 1997).

[0007] Furthermore, the recognition site of CR-50 is confirmed to be placed between a F-spondin domain and a Reelin repeat I (J. Neurosci., 17, 23-31, 1997).

[0008] Based on the above background, the N-terminal of Reelin is a site directly involved in Reelin function. Moreover, Reelin repeat is thought to localize Reelin proteins as ECM-like molecules in the vicinity of Reelin-producing cells, such as Cajal-Retzius cells, so as to give more localized signals.

SUMMARY OF THE INVENTION

[0009] An object of the present invention is to confirm the presence of a Reelin (herein after referred as “Reelin”) protein in Amphibian whose brain is normally shown to have no laminated structure.

[0010] The inventors cloned Reelin homologous molecules of Xenopus and confirmed the presence of a truncated isoform produced by alternative splicing during the process. This isoform has a F-spondin domain and a CR-50 recognition site, but has no Reelin repeat (hereinafter referred to as “repeat site.”). Moreover, the inventors showed that this type of isoform is also present in a mouse. Since these isoforms have no repeat site, it is thought that they have no properties of an ECM-like molecule but play a role as humoral factors distributed distantly. The inventors completed this invention based on these understandings.

[0011] The present invention is summarized as follows.

[0012] (1) A truncated Reelin protein comprising an F-spondin domain and a CR-50 recognition site of a Reelin protein but containing no repeat site.

[0013] (2) The truncated Reelin protein of (1) which is derived from Xenopus or mice.

[0014] (3) The truncated Reelin protein of (2) which is either one of the following proteins (a) or (b):

[0015] (a) a protein consisting of an amino acid sequence represented by SEQ ID NO: 2,

[0016] (b) a protein consisting of an amino acid sequence differing from the amino acid sequence of SEQ ID NO: 2 by deletion, substitution, or addition of one or more amino acids, and having Reelin protein activity.

[0017] (4) The truncated Reelin protein of (2) which is either one of the following proteins (a) or (b):

[0018] (a) a protein consisting of an amino acid sequence represented by SEQ ID NO: 4,

[0019] (b) a protein consisting of an amino acid sequence differing from the amino acid sequence of SEQ ID NO: 4 by deletion, substitution, or addition of one or more amino acids, and having Reelin protein activity.

[0020] (5) A DNA encoding a truncated Reelin protein comprising an F-spondin domain and a CR-50 recognition site of a Reelin protein but contains no repeat site.

[0021] (6) The DNA of (5) which is derived from Xenopus or mice.

[0022] (7) The DNA of (6) encoding a truncated Reelin protein which is either one of the following proteins (a) or (b):

[0023] (a) a protein consisting of an amino acid sequence represented by SEQ ID NO: 2,

[0024] (b) a protein consisting of an amino acid sequence differing from the amino acid sequence of SEQ ID NO: 2 by deletion, substitution, or addition of one or more amino acids, and having Reelin protein activity.

[0025] (8) The DNA of (7), which is any one of the following DNAs (a) to (c):

[0026] (a) a DNA having a nucleotide sequence represented by SEQ ID NO: 1,

[0027] (b) a DNA hybridizing to a nucleic acid probe which comprises a sequence of 1456^(th) to 2273^(rd) nucleotide in the nucleotide sequence of SEQ ID NO: 1 under stringent conditions [for example, at 42° C. in the presence of 5×SSPE and 50% formamide (20×SSPE 3 M NaCl, 173 mM NaH₂PO₄, 25 mM EDTA)], and encoding a protein having Reelin protein activity.

[0028] (c) a DNA having a nucleotide sequence which is a degenerate sequence of that of the DNA (a) or (b).

[0029] (9) The DNA of (6) encoding either one of the following truncated Reelin proteins (a) or (b):

[0030] (a) A protein comprising an amino acid sequence represented by SEQ ID NO: 4,

[0031] (b) a protein comprising an amino acid sequence differing from the amino acid sequence of SEQ ID NO: 4 by deletion, substitution, or addition of one or more amino acids, and having Reelin protein activity.

[0032] (10) The DNA of (9) which is any one of the following DNAs (a) to (c):

[0033] (a) a DNA having a nucleotide sequence represented by SEQ ID NO: 3,

[0034] (b) A DNA hybridizing to a nucleic acid probe which comprises a sequence of 2053^(rd) to 2758^(th) nucleotides in the nucleotide sequence of SEQ ID NO: 3 under stringent conditions [for example, at 42° C. in the presence of 5×SSPE and 50% formamide (20×SSPE=3 M NaCl, 173 mM NaH₂PO₄, 25 mM EDTA)], and encoding a protein having Reelin protein activity, or

[0035] (c) A DNA having a nucleotide sequence which is a degenerate sequence of that of the DNA (a) or (b).

[0036] In this specification the term “Reelin protein” means a causative gene of Reeler mutant mice and an extracellular matrix protein comprising a signal peptide, F-spondin domain, CR-50 recognition site, and Reelin repeat.

[0037] The term “F-spondin domain” is a region that is shown to have homology with F-spondin on the N-terminal side of a Reelin protein.

[0038] The term “CR-50 recognition site” is a site that a CR-50 antibody recognizes in a mouse Reelin protein, and a region homologous to the CR-50 recognition site of mouse Reelin in a Reelin protein of other organisms. CR-50 antibodies can be prepared by the method described in Neuron 14, 899-912, 1995.

[0039] The term “repeat site” is a region on the C-terminal side of a Reelin protein that contains repeating units which consist of an amino acid sequence with an EGF-like motif at its center, and which are homologous to one other.

[0040] The term “Reelin protein activity” includes any biological and immunological action that a Reelin protein possesses. An example is the function of aligning neurons in their correct positions. This can be confirmed by the methods described in Nature 385, 70-74, 1997, J. Neurosci., 17, 3599-3609, 1997, and Proc. Natul. Acad. Sci. USA, 94, 8196-8201, 1997.

[0041] Reelin is an essential molecule in developing a normal laminated structure of cerebrum. Though no laminated structure is observed in Amphibian cerebrum, Xenopus Reelin was searched to confirm whether Reelin molecules are present in such an organism.

[0042] As a result of PCR using degenerate primers, PCR fragments of Xenopus Reelin (Xreelin) were obtained. Surprisingly, 3′-RACE analysis revealed the presence of a splicing mutant which contains most of the F-spondin domain and hinge region on the N-terminal side of Xreelin, but contains no repeat site. Expression of both an intact form of Xreelin and a truncated form of Xreelin started at the tail bud embryonic stage (st. 28) and continued until the end of the development into an adult. Northern blotting showed that a transcript of the intact Xreelin was about 12 kb, as in a mouse. On the other hand, a band of the truncated Xreelin was confirmed at a 3 to 4 kb-position. Moreover, transcripts of the intact Xreelin were detected in the primordiums of the olfactory bulb and optic tectum by in situ hybridization. At tadpole stage (st. 47), expression of the transcripts was also confirmed in the cerebellum. These results were almost identical to those for mice, but no expression was observed in the cerebrum. This is consistent with the fact that Xenopus brain has no laminated structure.

[0043] The truncated Reelin protein of this invention contains no Reelin repeat which accounts for approximately 85% of a Reelin protein. Reelin repeat is a region containing 8 repeats of a sequence having an EGF-like motif, suggesting that it binds with an extracellular matrix molecule having another EGF-like motif. Accordingly, Reelin repeat is a region required to localize Reelin proteins in extracellular matrix and a truncated isoform lacking this repeat site may diffuse farther in vivo.

[0044] For example, diseases including agyria, polymicrogyriam, and ectopic gray matter due to abnormal neuronal alignment can be treated by incorporating cDNA encoding truncated Reelin proteins of this invention into expression vectors, introducing the vectors into neuroblasts and nerve trunk cells and the like derived from the tissue of a patient, and transplanting those cells into the patient brain.

SEQUENCE LISTING FREE TEXT

[0045] SEQ ID NOS: 5 to 17, 19, 20, and 22 to 28 show nucleotide sequences of primers.

[0046] SEQ ID NOS: 18 and 20 show nucleotide sequences of probes.

BRIEF DESCRIPTION OF THE DRAWINGS

[0047]FIG. 1 shows nucleotide sequences of the intact form of a Xenopus Reelin protein (Xreelin) (A) and of the truncated isoform (B) and a putative amino acid sequence of a Xenopus Reelin protein. “*” indicates a stop codon. Amino acids within a region pointed with an arrow (▾) are contained in the intact form of Reelin protein but not in the truncated isoform. A polyadenylation signal located 15 nucleotides upstream of a polyadenylation site is underlined.

[0048]FIG. 2A shows multiple alignments of putative amino acids of Xenopus, mouse and human Reelin proteins. Putative signal peptides deduced based on Signalase software are underlined with broken lines. F-spondin domains are underlined with bold lines. Regions surrounded with frames contain amino acid residues common among all of the three types. Gaps inserted are shown with “−.” Amino acid residues identical to those of Xreelin are shown with .

[0049]FIG. 2B is a diagram showing a mouse Reelin protein, Xreelin and truncated Xreelin. Undefined regions are shown with a broken line. Regions enclosed with frames denote coding regions and lines denote noncoding regions.

[0050]FIG. 3A shows the results of Northern blot analysis on Xreelin. A bold arrow (←) indicates the intact form of a Reelin protein and an arrow (

) indicates the truncated form of a Reelin protein.

[0051]FIG. 3B shows the results of Western blot analysis on Xreelin. A bold arrow (←) shows a Xreelin protein of the same size as a mouse Reelin protein detected with a Reelin protein antibody 142. A thin arrow (←) indicates a Xreelin protein fragment slightly smaller than a mouse Reelin protein fragment processed with metallo proteinase. An arrow (

) indicates a protein with a size predicted to be the truncated form of a Reelin protein.

[0052]FIG. 4 shows the results of RT-PCR using RNA samples at various developmental stages. At the top of a panel are numbers of developmental stages of samples in each lane.

[0053]FIG. 5 shows the distribution of the intact form of Xreelin mRNA by in situ hybridization (FIG. 5A, B, C, D, E, F). Anti-sense probes to XdII (D) and Eomesodermin (F) were also used to define the region of striatum in telencephalon and mitral cell in olfactory bulb. The specimens employed were (A) st. 35/36 whole embryos, (B) st. 47 whole brain, (E, F) horizontal sections of st. 51 olfactory bulb, and coronal sections of st. 54 at the level of (C, D) telencephalon, (G) tactum, and (H) spinal cord.

[0054] a: antisense probe, cp: cerebellum primordium, ob: olfactory bulb, s: sense probe, tec: tectum, Scale bars: A, B, 500 μm; C, D, G, H, 100 μm; E. F, 200 μm.

[0055]FIG. 6 shows the comparison of expression pattern of the intact and truncated forms of Xreelin mRNA by in situ hybridization (A to C) and TaqMan PCR analysis (D). The intact (A) and truncated forms (B) of Xreelin mRNA in the horizontal section of st. 51 cerebellum were detected. The neighboring section was hybridized to sense probe of the intact form (C). Scale bars: 100 μm. The total RNA of seven parts of Xenopus brain (E) was subjected to TaqMan PCR analysis. Unfilled bars and filled bars indicate the copy number of intact and truncated forms, respectively.

EXAMPLE

[0056] Now, a detailed description of the present invention will be given as follows. These examples are intended as an explanation, but do not limit the scope of the invention.

Example 1 Cloning of Xenopus Reelin (Xreelin)

[0057] Method

[0058] Random primed cDNA was synthesized from total RNA purified from stage (st.) 35 (Nieuwkoop, P. D. & Faber, J, 1967, in Normal Table of Xenopus laeis (Daudin), North-Holland Publishing Company, Amsterdam) Xenopus whole embryos using Super Script II (Gibco BRL), and subjected to PCR with degenerate primers. Using a set of degenerate primers [5′-A(A/G)TT(T/C)GGIAA(T/C)CA(A/G)TT(T/C)ATGTG-3′ (SEQ ID NO; 5) and 5′-TG(T/C)TCICCCAT(T/C)CA(A/G)TT-3′ (SEQ ID NO: 6)], the PCR fragment of Xreelin, which corresponds to 362 to 696 in the nucleotide sequence in FIG. 1 was obtained. To obtain the sequence further upstream from the PCR product, 5′ RACE (5′-rapid amplification of cDNA end) was performed. Poly (A)+RNA was purified from the total RNA isolated from st. 35 Xenopus whole embryo using a Fast Track 2.0 kit (Invitrogen). The later procedures were carried out using Gibco 5′ RACE system ver. 2 (GC rich protocol, Gibco BRL). First strand synthesis was primed with a gene specific primer [5′-ATGTCCTCACTGGAAAGATC-3′ (SEQ ID NO: 7)]. The purified product of second strand reaction was A-tailed, and PCR performed thereon using the AUAP primer (Gibco BRL) and gene specific primer [5′-CAGCAACACATAGGGGACAA-3′ (SEQ ID NO: 8)]. Moreover, 3′ RACE (3′-rapid amplification of cDNA end) was conducted using 3′ RACE system (Gibco BRL). First strand cDNA was generated by Super Script II with oligonucleotide [5′-GGCCACGCGTCGACTAGTACGAATTCATCTATAGC(T)₁₇-3′ (SEQ ID NO: 9)] from total RNA of st. 35 Xenopus whole embryos. PCR was performed with an adapter primer, the sequence of which is the complement of the oligonucleotide described above without (T)₁₇ and a gene specific primer [5′-CAGTGTCGTTGCTTCCCACGTGAGTCATCTTCCCA-3′ (SEQ ID NO: 10)]. This PCR product was further amplified with the adapter primer and a nested gene specific primer [5′-CGACAGGTACAGGATGTGTCAACTTCATGGCCACA-3′ (SEQ ID NO: 11)]. A single band was obtained from this step, and was cloned into pGEM-T Easy vector (Promega). By sequencing this clone, a truncated isoform generated by alternative splicing was identified. The intact form specific sequence was elucidated by screening of the cDNA library. The Poly (A)+RNA prepared by Fast Track 2.0 kit from st. 56 Xenopus tadpole was employed to first strand synthesis in addition to the use of oligo(dT)₁₂₋₁₈ and random hexamers. The synthesized cDNA was ligated to λ ZapII phage vector (Stratagene). The 1×10⁶ independent clones were screened by a ³²P labeled probe corresponding to 414 to 1253 nucleotides in the nucleotide sequence in FIG. 1. Thus 2 clones were isolated and sequenced. Sequencing of these clones revealed the nucleotide sequence of the intact form (1294 to 1869). The nucleotide sequences shown in FIG. 1 were confirmed by at least 3 rounds of separate PCR reactions.

[0059] Results

[0060] To obtain the Xenopus counterpart of Reelin, several sets of degenerate PCR primers were designed for various regions of the mouse Reelin. Among these primers, primer sets which enclose the boundary between the F-spondin domain and the CR-50 epitope region amplified a fragment with a sequence highly homologous to the mouse/human Reelin. Then 5′ RACE and screening of a cDNA library were performed so that the 5′-non-coding region of 156 base pairs (bp) and the coding region of 1873 bp were isolated (FIG. 1A). These sequences were confirmed by sequencing three independent PCR products. Comparison of the amino acid sequence of Reelin between the lower vertebrate and mouse/human clarified the region conserved in evolution (D' Arcangelo, G., Miao, G. G., Shu-Cheng, C., Soares, H. D., Morgan, J. I. & Curran, T., 1995, Nature 374, 719-723; DeSilva, U., D' Arcangelo G., Braden, V., Chen, J., Miao, G., Curran, T. & Green, E. D., 1997, Genome res. 7, 157-164). The deduced amino acid sequence of Xreelin is conserved as between mouse/human Reelin over the extent of the sequenced region, but especially in the F-spondin domain. The identity and similarity within the F-spondin domain are estimated 93.2% and 95.1%, respectively, whereas the identity and similarity of the hinge region, which contains the CR-50 epitope region and is between the F-spondin domain and Reelin repeats, 77.2% and 84.6%, respectively (FIGS. 2A and 2B). These results strongly suggest that the F-spondin domain is functionally important. This finding is particularly interesting as the inventors reported previously that CR-50, which recognizes just downstream of the F-spondin domain, blocks Reelin function both in vitro and in vivo (Ogawa, M., Miyata, T., Nakajima, K., Yagyu, K., Seike, M., Ikenaka, K., Yamamoto, H. & Mikoshiba, K., 19956, Neuron 14, 899-912; Del Rio, J. A., Heimrich, B., Borrell, V., Forster, E., Drakew, A., Alcantara S., Nakajima, K., Miyata, T., Ogawa, M., Mikoshiba, K., Derer, P., Frotscher, M. & Soriano, E., 1997, Nature 385, 70-74; Miyata, T., Nakajima, K., Mikoshiba, K. & Ogawa, M., 1997, J. Neurosci. 17, 3599-3609.; Nakajima, K., Mikoshiba, K., Miyata, T., Kudo, C. & Ogawa, M., 1997, Proc. Natl. Acad. Sci. USA 94, 8196-8201.

[0061] To obtain sequence information on downstream of the cloned region, 3′-RACE was performed. Thus, a truncated isoform of Xreelin containing only the F-spondin domain and the CR-50 epitope region was identified (FIGS. 1B and 2B). Interestingly and surprisingly, this novel isoform does not have any Reelin repeat. On this truncated isoform, the nucleotide sequence differs from that of the intact form from the second nucleotide of the TGG codon. That is, the TGG is changed to TAA. This difference coverts the amino acid, tryptophan 433, to a stop codon TAA. Thereafter, a non-coding region of 698 bp follows, and poly-adenylation signal (AATAAA) appears at 15 bp upstream of the poly-adenylation site. The nucleotides that differ between the intact form and the truncated form correspond to the end of exon #11 of mouse Reelin (Royaux, I., Lambert de Rouvroit, C., D' Arcangelo, G., Demirov, D. & Goffinet, A. M., 1997, Genomics 46, 240-250). Analysis of how this isoform is generated is not yet complete but the most likely explanation is the skipping of splicing and reading into intron #11. PCR amplification using a forward primer to both isoforms and a reverse primer specific only to the truncated form was done on either genomic DNA or random primed cDNA as a template. Both gave an amplified product of the same size, which is compatible with the skipping of splicing mechanism.

Example 2 Northern Blot Analysis

[0062] Method

[0063] Five grams of poly (A)+RNA prepared from st. 50, 56, and 60 Xenopus tadpole head was applied on each lane, subjected to electrophoresis, and then transferred to Zeta-Probe Blotting membrane (Bio-Rad). 32 P labeled RNA probes were synthesized by in vitro transcription with [α-32P] UTP and [α-32P] CTP using the sequence common to the intact and truncated form, and the 3′-noncoding region of the truncated form which corresponds to nucleotides 414-1253 and 1302-2099, respectively. Hybridization was carried out in 5×SSPE/50% formamide+5× Denhart's solution+0.5% SDS at 60° C. over night. The filter was washed twice in 2×SSC+0.1% SDS at 60° C. for 30 minutes, and then in 0.1×SSC+0.1% SDS at 60° C. for 30 minutes.

[0064] Results

[0065] To confirm the presence of this novel isoform, Northern blot analysis was performed (FIG. 3). Using an RNA probe to a sequence common to both forms, a transcript of 12 to 13 kb was detected. This result indicates that there is indeed an intact form of Reelin in Xenopus as a huge molecule like that found in mice. Apart from this transcript, a transcript of 2.8 kb was also found. Moreover, when the 3′ non-coding region was used as a probe, only the shorter transcript of 2.8 kb was detected. The truncated form has a coding region of 1299 bases (b) and a 3′ untranslated region of 698 bases, and, so far, 156 bases of the 5′ untranslated region have been cloned and sequenced. Therefore, the mRNA of the truncated from is expected to consist of at least 2153 nucleotides. The size of the detected band on Northern blot analysis is larger than this size, but it is supposed that this discrepancy result from the unidentified region of the 5′ terminal untranslated region. Thus, it is concluded that mRNA of the truncated form certainly exists.

Example 3 Determination by RT-PCR of the Time of Xreelin mRNA Expression

[0066] Method

[0067] Total RNA was prepared from 2 cell stage and stage 7, 8, 10/11, 12.5, 13, 15, 19, 22, 28, 35/36, 42 and 50 of whole embryo and adult brain. Reverse transcription was performed from 1 g of total RNA, and {fraction (1/40)} of the RT products was subjected to PCR using ³²P-dCTP. The PCR primers were designed in the common region between the intact and the truncated forms [5′-TCCCACAACAAACCTAAGTT-3′ (SEQ ID NO: 12) and 5′-ATGTCCTCACTGGAAAGATC-3′ (SEQ ID NO: 13)]. PCR for Histon H4 was also performed using the same templates as a control: [5′-CGGGATAACATTCAGGGTATCACT-3′ (SEQ ID NO: 14) and 5′-ATCCATGGCGGTAACTGTCTTCCT-3′ (SEQ ID NO: 15)]. The number of cycles was 24 and 19 for Xreelin and Histon H4, respectively.

[0068] Results

[0069] The time course of Xreelin expression at the transcription level was determined by RT-PCR (FIG. 4A). The primer set used in this assay was designed to amplify the common sequence between the intact form and the truncated form. To normalize each sample, PCR using a primer set for Histon H4 was performed. No Xreelin mRNA was detected during early development, and it first appeared in late neurula (st. 28). In tadpole stages, the signals became much stronger than those in neurula. Xreelin transcripts were also detected in the adult brain. In mouse development, Reelin mRNA becomes detectable after E8 by in situ hybridization and continues to be expressed in the adult brain (Ikeda, Y. & Terashima, T., 1997, Dev. Dyn. 210, 157-172; Schiffmann, S. N., Bernier, B. & Goffinet, A. M., 1997, European Journal of Neuroscience 9, 1055-1071.; Alcantara, S., Ruiz, M., D' Arcangelo, G., Ezan, F., de Lecea, L. & Curran, T., 1998, J. neurosci. 18, 7779-7799). Since the late neurula in Xenopus development is the switching point between neurulation and morphogenesis of the CNS, this stage corresponds to E8 of the mouse embryo in neural development. Therefore, the time course of Xreelin expression is similar to that of the mouse Reelin.

Example 4 Quantification of the Intact and the Truncated Form-mRNA Method

[0070] The amount of transcripts of the intact and truncated forms of Xreelin was evaluated by ABI PRISM 7700 (Perkin Elmer) using the gene-specific primers and oligonucleotide probes coupled with FAM (5-carboxyfluorescein) at the 5′ end and TAMRA (N, N, N′-tetramethyl-5-carboxyrhodamine) at the 3′ end (TaqMan probes). Total RNA was prepared from various stages (2-cell stage, st. 22, st. 28 and st. 43 whole embryos) and various parts of st. 50-54 brain (FIG. 5C). Reverse transcription (RT) was performed from 1 g of these RNA samples using Super Script II (Gibeo BRL) and random hexamer, and {fraction (1/40)} of the products was subjected to PCR using TaqMan probes. The procedure for this PCR was according to the protocol of TaqMan PCR Reagent Kit (Perkin Elmer). At each point, the averages and standard deviations were obtained by three independent PCR from one RT-product. To detect the intact form, one set of primers [5′-GTCCTGATCTACAAACACCTGCTACT-3′ (SEQ ID NO: 16) and 5′-AGGTAGCACATGGACAAAATCC-3′ (SEQ ID NO: 17)] and a TaqMan probe [5′-(FAM)CTGAAGCAAACCAGTCACCGTGGTCA(TAMRA)-3′ (SEQ ID NO: 18)] were used. For the truncated form, the primer set [5′-TAGTGAGTGTGACAATCAGAAGTGA-3′ (SEQ ID NO: 19)] and [5′-GGCCCTTTCTGGATAAGAATC-3′ (SEQ ID NO: 20)], and a TaqMan-probe [5′-(FAM)TCAACCATTTGCTCATACAGATGCACA(TAMRA)-3′ (SEQ ID NO: 21)] were used. The copy numbers were estimated by a standard curve made from a dilution-series of plasmid DNA containing the intact form or the truncated form-specific sequence.

[0071] Results

[0072] Then the developmental profile of the truncated in comparison with the intact form was examined. To address this issue, the amount of intact form and truncated form RNA was determined at several time-points (FIG. 4B). The amount of RNA was quantified by the TaqMan PCR technique using probes labeled with fluorescent dye, FAM and TAMRA, on the 5′ and 3′ ends, and then the degradation of the probe was observed during PCR. Expression of the truncated from is first observed around st. 28 and become much stronger in the later stages. This expression pattern resembles that of the intact form, and the proportion of the amount of truncated form versus intact form is constantly 5 to 10% throughout development. These results indicate that the expression profile of the both forms during development is regulated in the same way, although the absolute amounts differ.

Example 5 Analysis of Xreelin mRNA Localization by In Situ Hybridization

[0073] Method

[0074] The SDS-based in situ hybridization protocol was used (Shain, D. H. & Zuber, M. X., 1996, J. Biochem. Biophys. Methods 31, 185-188). Whole embryos of st. 35/36 were fixed in MEMFA buffer (Harland, R. M. in Methods in Cell biology, 1991, Academic Press Inc., San Diego, pp685-694) for 90 min. The brains of st.47 were dissected out in MEMFA and fixed in fresh MEMFA for 90 min. The digoxygenin labeled-RNA probe was synthesized by in vitro transcription using plasmid DNA containing the nucleotide sequence corresponding to 414-1252 in FIG. 1A as a template. The alkaline phosphatase chromogenic reaction was carried out in Purple AP (Boehringer-Manheim) for several hours at room temperature. The brain of st. 51 was dissected out in 4% paraformaldehyde in 70% PBS, and fixed in fresh same fixative overnight. The specimens embedded in OCT compound (Tissue Tech) were sectioned in 20 μm thick, and employed to in situ hybridization on the same way as for the whole embryos/brains with the exception that the NBT/BCIP solution in alkaline phosphatase buffer was used in the step of chromogenic reaction. RNA probes to the intact and truncated forms were synthesized from the sequences corresponded to 1296 to 1825 in FIGS. 1A and 1302 to 2099 in FIG. 1B, respectively. RNA probes to XdII and eomesodermin were prepared from the plasmid containing the PCR fragment obtained by using each gene-specific primers [5′-CCTCCAAGTCTGCCTTTATG-3′ (SEQ ID NO: 22) and 5′-GCGGACAACAATATGCAAGG-3′ (SEQ ID NO: 23)] for XdII, and [5′-GCGGACAACAATATGCAAGG-3′ (SEQ ID NO: 24) and 5′-GGTTGTTGACAAACTGGTCC-3′ (SEQ ID NO: 25)] for eomesodermin from the cDNA prepared from st. 51 Xenopus tadpole.

[0075] Results

[0076] Reelin molecule is required for well-arranged lamination in the mouse brain development. Whereas the Reelin counterpart exists in Xenopus, its telencephalon shows no obvious laminated structure. Therefore, it is important whether or not Xreelin is expressed in the Xenopus dorsal pallium, which is a homologue of the mouse neocortex (Northcutt, G. R. & Kaas, J. H., 1995, Trends Neurosci 18, 373-379,; Fernandez, A. S., Pieau, C., Reperant, J., Boncinelli, E. & Wassf, M., 1998, Development 125, 2099-2111). To address this point, the distribution of Xreelin mRNA in telencephalon was examined more precisely. XdII is a Xenopus counterpart of distalless (Asano, M., Emori, Y., Saigo, K. & Shiokawa, K., 1992, J. Biol. Chem. 267, 5044-5047), and known to be expressed in the striatum (Asano, M., Emori, Y., Saigo, K. & Shiokawa, K., 1992, J. Biol. Chem. 267, 5044-5047). XdII mRNA is localized in the ventral side of telencephalon (FIG. 5D), and the Xreelin transcript is found more dorsally (lateral pallium) to the XdII-positive region (FIG. 5C). In the dorsal pallium, which is lying dorsally to the lateral pallium, Xreelin is expressed weakly in a few scattered cells near the surface of the telencephalic vesicle. These cells might correspond to the Cajal-Retzois cells of the mouse neocortex and have some function in the morphogenetic events other than the multi-layer alignment of neuroblasts.

[0077] In developing olfactory bulb of a mouse, the Reelin transcript is expressed in mitral cells. The Xreelin-expressing cells were identified in the olfactory bulb in Xenopus. Eomesodermin (Eomd) is known to be specifically expressed in mitral cells of the olfactory bulb (Ryan, K., Garett, N., Mitchell, A. & Gurdon, J. B., 1996, Cell 87, 989-1000; Ryan, K., Butler, K., Bellefroid, E. & Burdon, J. B., 1998, Mech. Dev. 75, 167-170). Using a probe to Eomd, it was clarified that the mitral cells are arranged in a “V” shaped pattern on horizontal sections of st. 51 olfactory bulb (FIG. 5F), and the Xreelin transcript is detected in the same pattern (FIG. 5E). In consequently, it is concluded that Xreelin is expressed in mitral cells in the developing olfactory bulb.

[0078] Whole mount in situ hybridization of brains revealed that Xreelin is expressed in the tectum (FIG. 5B). To elucidate the localization of Xreelin-expressing cells in detail, an Xreelin-specific probe was used to hybridize cross sections of st. 54 tectum. Xreelin was found beneath the stratum opticum, which is the most superficial layer of the tectum (FIG. 5B). The retinal axons coming through the stratum opticum turn into the underlying multiple cell-layers and terminate at a specific subset of lamina. So far, the distribution of mouse Reelin mRNA in the superior colliculus has not been reported in detail. However, homozygous Reeler mice show some abnormality in the retinotectal projection, whereas the cytoarchitecture itself is rather normal (Frost, D. O., Edwards, M. A., Sachs, G. M. & Caviness, V. J., 1986, Brain Res 393, 109-20). Taken together, these data suggest that Xreelin has some role in retinotectal projection during development.

[0079] In the spinal cord, Xreelin signals are found mainly in the medial to intermedio-lateral portions slightly ventral to the middle plane between the dorsal extremity and the ventral extremity. Weak signals are also detected in the dorsal horn (FIG. 5H). These expression patterns are similar to those in mice (Ikeda, Y. & Terashima, T., 1997, Dev. Dyn. 210, 157-172; Schiffmann, S. N., Bernier, B. & Goffinete, A. M., 1997, European Journal of Neuroscience 9, 1055-1071; Alcanara, S., Ruiz, M., D'Arcangelo, G., Ezan, F., De Lecea, L. & Curran, T., 1998, J. Neurosci. 18, 7779-7799).

[0080] To investigate the localization of the truncated form of Xreelin, in situ hybridization was carried out using a truncated form-specific probe. Thus, faint signals were detected in the cerebellum (FIG. 6B) in a similar pattern to the intact form (FIG. 6A), but no in situ signal was detected in other regions. Next, TaqMan PCR analysis was performed using RNA from various brain regions of Xenopus (FIGS. 6C and 6D). A large amount of the intact form mRNA was found in the olfactory bulb, tectum and cerebellum, which was compatible with the expression pattern revealed by in situ hybridization. On the other hand, the truncated form of Xreelin was distributed in a similar manner to the intact form, and the ratio of the truncated form to the intact form was about 10% in each region. Considering the results obtained at various stages (FIG. 4B), it is likely that the expression profile of both forms is regulated by a common mechanism.

Example 6 Existence of Truncated Reelin Protein in Mice

[0081] Protocol

[0082] Mouse truncated Reelin protein was confirmed to exist by 3′-RACE. Total RNA was extracted from the spinal cord excised from a Reeler heterologous embryo on day 18 of the embryonal stage (the genotype had been specified by PCR). First strand synthesis using a primer [5′-GGCCACGCGTCGACTAGTACGAATTCATCTATAGC(T)₁₇-3′ (SEQ ID NO: 9)], and then PCR using an Adaptor primer AP2 [5′-CGCGTCGACTAGTACGAATT-3′ (SEQ ID NO: 26)] and a Reelin gene-specific primer RL-11 [5′-CTGATTGGATTCAGCTGGAG-3′ (SEQ ID NO: 27)] were performed. Further, the PCR product was subjected to nested PCR using AP2 and a Reelin gene-specific primer RL-12 [5′-ATTCAGCCCACAGAGAAGTC-3′ (SEQ ID NO: 28)].

[0083] Results

[0084] Three bands were confirmed by the PCR. The bands were separately incorporated into PGEM-T Easy vectors, and sequenced. Thus, one of them was an alternative splicing product which contains up to exon14 of mouse Reelin followed by an unknown sequence. The difference between the alternative splicing product and a full length Reelin protein is replacement of the final amino acid of exon14, serine by arginine immediately followed by a termination codon. Therefore, the alternative splicing product was determined to be the truncated form. At the end of the 3′-untranslated region of the mouse truncated Reelin, multiple poly-adenylation signals (AATAAA) were confirmed.

[0085] The truncated Reelin protein of this invention and DNA encoding the protein can be used for treatment of diseases including agyria due to abnormal neuronal alignment.

1 28 1 2274 DNA Xenopus laevis misc_feature (100) a or g or t or c 1 cattctactg tcacgttaac tttccatttt cttcacttta actttgaaga atttaaaaaa 60 aaccattaat tatatattta tataaatata tatatataan ctctgtatcc caggctgctt 120 atgaagaaag ctcattaaga acagtgggac ccagga atg gaa ctg ctc cac acc 174 Met Glu Leu Leu His Thr 1 5 ttc tgc ggt ggg cgc tgg act ttg ctg ctc ttc acg ggg atc ttg tgc 222 Phe Cys Gly Gly Arg Trp Thr Leu Leu Leu Phe Thr Gly Ile Leu Cys 10 15 20 ttt gtt gtt gcc cgc gga gtg ggg tat tat ccc agg ttc tct cca ttc 270 Phe Val Val Ala Arg Gly Val Gly Tyr Tyr Pro Arg Phe Ser Pro Phe 25 30 35 ttt ttc ctt tgc act cat cat gga gaa ctg gaa gga gat ggg gaa caa 318 Phe Phe Leu Cys Thr His His Gly Glu Leu Glu Gly Asp Gly Glu Gln 40 45 50 gga gaa gtg ctc atc tct ctg cac ctg gcg ggc aac ccc agc tac tac 366 Gly Glu Val Leu Ile Ser Leu His Leu Ala Gly Asn Pro Ser Tyr Tyr 55 60 65 70 ata cct ggg cag gag tac cat gtg acc ata tcc act agt acc ttc ttt 414 Ile Pro Gly Gln Glu Tyr His Val Thr Ile Ser Thr Ser Thr Phe Phe 75 80 85 gat ggt ctt ctg gtg act gga ctt tac act tct acc agt gtt caa gcg 462 Asp Gly Leu Leu Val Thr Gly Leu Tyr Thr Ser Thr Ser Val Gln Ala 90 95 100 tct cag agc att gga ggc tct aaa gca ttt gga ttt ggt att atg agc 510 Ser Gln Ser Ile Gly Gly Ser Lys Ala Phe Gly Phe Gly Ile Met Ser 105 110 115 gac cgt cag ttt ggt acc cag ttt atg tgc agt gtc gtt gct tcc cac 558 Asp Arg Gln Phe Gly Thr Gln Phe Met Cys Ser Val Val Ala Ser His 120 125 130 gtg agt cat ctt ccc aca aca aac cta agt ttt gta tgg att gca cca 606 Val Ser His Leu Pro Thr Thr Asn Leu Ser Phe Val Trp Ile Ala Pro 135 140 145 150 cca gca ggt aca gga tgt gtc aac ttc atg gcc aca gca aca cat agg 654 Pro Ala Gly Thr Gly Cys Val Asn Phe Met Ala Thr Ala Thr His Arg 155 160 165 gga caa gtt att ttc aag gat gcc ctg gca caa caa ctg tgc gaa caa 702 Gly Gln Val Ile Phe Lys Asp Ala Leu Ala Gln Gln Leu Cys Glu Gln 170 175 180 gga gct cct act gaa gct ccc ttg cgg cct aat tta gcc gaa att cac 750 Gly Ala Pro Thr Glu Ala Pro Leu Arg Pro Asn Leu Ala Glu Ile His 185 190 195 agt gaa agc atc ctt tta cga gat gat ttt gac tca tat aag ctt cag 798 Ser Glu Ser Ile Leu Leu Arg Asp Asp Phe Asp Ser Tyr Lys Leu Gln 200 205 210 gaa ttg aat cca aat att tgg ctc cag tgc aga aat tgc gaa gtt ggt 846 Glu Leu Asn Pro Asn Ile Trp Leu Gln Cys Arg Asn Cys Glu Val Gly 215 220 225 230 gag cag tgt ggt gca att atg cat ggt ggg gca gtc act ttt tgt gat 894 Glu Gln Cys Gly Ala Ile Met His Gly Gly Ala Val Thr Phe Cys Asp 235 240 245 ccg tat gga cca aga gaa ttg ata act gtt caa atg aac aca act acg 942 Pro Tyr Gly Pro Arg Glu Leu Ile Thr Val Gln Met Asn Thr Thr Thr 250 255 260 gca tct gtt ttg cag ttt tct att ggg tca gga tcg tgc agg ttc agc 990 Ala Ser Val Leu Gln Phe Ser Ile Gly Ser Gly Ser Cys Arg Phe Ser 265 270 275 tat tca gac cct gga att gtg gtg tca tac aca aag aat aat tca tct 1038 Tyr Ser Asp Pro Gly Ile Val Val Ser Tyr Thr Lys Asn Asn Ser Ser 280 285 290 agt tgg atg cca ttg gag aga att agt gct cct tcc aat gtt agc acc 1086 Ser Trp Met Pro Leu Glu Arg Ile Ser Ala Pro Ser Asn Val Ser Thr 295 300 305 310 atc att cac att att tac cta cct cct gaa gct aaa gga gaa aat gtg 1134 Ile Ile His Ile Ile Tyr Leu Pro Pro Glu Ala Lys Gly Glu Asn Val 315 320 325 aaa ttc cgt tgg agg cag gag aac atg cag gca ggt gat gtg tat gaa 1182 Lys Phe Arg Trp Arg Gln Glu Asn Met Gln Ala Gly Asp Val Tyr Glu 330 335 340 gcc tgc tgg gca ctg gat aac att ttg att atc aat gct gct cat aaa 1230 Ala Cys Trp Ala Leu Asp Asn Ile Leu Ile Ile Asn Ala Ala His Lys 345 350 355 gaa gtc gtg tta gaa gac aat cta gat cca atg gac aca gga aac tgg 1278 Glu Val Val Leu Glu Asp Asn Leu Asp Pro Met Asp Thr Gly Asn Trp 360 365 370 ctt ttt ttc cct ggg gct act gta aag cat acc tgt cag tcg gat gga 1326 Leu Phe Phe Pro Gly Ala Thr Val Lys His Thr Cys Gln Ser Asp Gly 375 380 385 390 aac tct ata tat ttt cat ggt aca gaa agc agt gaa tac aac ttt gct 1374 Asn Ser Ile Tyr Phe His Gly Thr Glu Ser Ser Glu Tyr Asn Phe Ala 395 400 405 act acc aga gat gtg gat ctt tcc agt gag gac atc cag gac cag tgg 1422 Thr Thr Arg Asp Val Asp Leu Ser Ser Glu Asp Ile Gln Asp Gln Trp 410 415 420 tct gaa gag ttt gag aat cta cca gct ggg taa attttagatg tagccatgag 1475 Ser Glu Glu Phe Glu Asn Leu Pro Ala Gly 425 430 cattacattt tatcacgtga aaatgcaaga aacagtattt atatacatat tttaaaggtc 1535 aatacagaac cctataaatg gcaggttagg gctaccatgt aaatattttt aatgttcata 1595 atgtcatagg tggtaagtat tttacatagc agttactgat tgattattat tgtttgtctt 1655 ttacccagtt acagctaaca cacagggcat ttttttccaa tggcaacatc cattttgccg 1715 ctctgagcag aacatttgtt tcatttatgg catttgaacc tgtgtctatg agagtgcagc 1775 taaaataaac ttcctggcta tgggtgttac catacaacac tggtacctca tgacatatga 1835 aaaatatgac tcacattaaa tcagtaagat cagttcaagt atagtacggt gcattaatct 1895 gccaataaac atttagaatt gtattttata ttttatattt aagattagaa ttgactccat 1955 tcttgtacct tgcatcacat ttgtggctag tttatgggtc aatagacagc catcatacat 2015 tagtcagagt aaatcgagca ttacaaaact caatgagcca tagtgagtgt gacaatcaga 2075 agtgactgtc aagtaaatca accatttgct catacagatg cacatttgaa cagtggattc 2135 ttatccagaa agggccattt tttactatca ctctgggatt taaatgccac ttctaattgg 2195 aacttccagg tcacaaaaat agaatggaca tttaaacatc atggttctca ttacccctaa 2255 taaaactccg gttttttta 2274 2 432 PRT Xenopus laevis 2 Met Glu Leu Leu His Thr Phe Cys Gly Gly Arg Trp Thr Leu Leu Leu 1 5 10 15 Phe Thr Gly Ile Leu Cys Phe Val Val Ala Arg Gly Val Gly Tyr Tyr 20 25 30 Pro Arg Phe Ser Pro Phe Phe Phe Leu Cys Thr His His Gly Glu Leu 35 40 45 Glu Gly Asp Gly Glu Gln Gly Glu Val Leu Ile Ser Leu His Leu Ala 50 55 60 Gly Asn Pro Ser Tyr Tyr Ile Pro Gly Gln Glu Tyr His Val Thr Ile 65 70 75 80 Ser Thr Ser Thr Phe Phe Asp Gly Leu Leu Val Thr Gly Leu Tyr Thr 85 90 95 Ser Thr Ser Val Gln Ala Ser Gln Ser Ile Gly Gly Ser Lys Ala Phe 100 105 110 Gly Phe Gly Ile Met Ser Asp Arg Gln Phe Gly Thr Gln Phe Met Cys 115 120 125 Ser Val Val Ala Ser His Val Ser His Leu Pro Thr Thr Asn Leu Ser 130 135 140 Phe Val Trp Ile Ala Pro Pro Ala Gly Thr Gly Cys Val Asn Phe Met 145 150 155 160 Ala Thr Ala Thr His Arg Gly Gln Val Ile Phe Lys Asp Ala Leu Ala 165 170 175 Gln Gln Leu Cys Glu Gln Gly Ala Pro Thr Glu Ala Pro Leu Arg Pro 180 185 190 Asn Leu Ala Glu Ile His Ser Glu Ser Ile Leu Leu Arg Asp Asp Phe 195 200 205 Asp Ser Tyr Lys Leu Gln Glu Leu Asn Pro Asn Ile Trp Leu Gln Cys 210 215 220 Arg Asn Cys Glu Val Gly Glu Gln Cys Gly Ala Ile Met His Gly Gly 225 230 235 240 Ala Val Thr Phe Cys Asp Pro Tyr Gly Pro Arg Glu Leu Ile Thr Val 245 250 255 Gln Met Asn Thr Thr Thr Ala Ser Val Leu Gln Phe Ser Ile Gly Ser 260 265 270 Gly Ser Cys Arg Phe Ser Tyr Ser Asp Pro Gly Ile Val Val Ser Tyr 275 280 285 Thr Lys Asn Asn Ser Ser Ser Trp Met Pro Leu Glu Arg Ile Ser Ala 290 295 300 Pro Ser Asn Val Ser Thr Ile Ile His Ile Ile Tyr Leu Pro Pro Glu 305 310 315 320 Ala Lys Gly Glu Asn Val Lys Phe Arg Trp Arg Gln Glu Asn Met Gln 325 330 335 Ala Gly Asp Val Tyr Glu Ala Cys Trp Ala Leu Asp Asn Ile Leu Ile 340 345 350 Ile Asn Ala Ala His Lys Glu Val Val Leu Glu Asp Asn Leu Asp Pro 355 360 365 Met Asp Thr Gly Asn Trp Leu Phe Phe Pro Gly Ala Thr Val Lys His 370 375 380 Thr Cys Gln Ser Asp Gly Asn Ser Ile Tyr Phe His Gly Thr Glu Ser 385 390 395 400 Ser Glu Tyr Asn Phe Ala Thr Thr Arg Asp Val Asp Leu Ser Ser Glu 405 410 415 Asp Ile Gln Asp Gln Trp Ser Glu Glu Phe Glu Asn Leu Pro Ala Gly 420 425 430 3 2745 DNA Mus musculus CDS (283)..(2052) sig_peptide (283)..(363) misc_feature (284)..(849) F-spondin domain 3 ggggcgtcgc gtgcacaccg gcggcggcgg cgctcggagg cggacgacgc gctctcggcg 60 cccgcggccc cggttccccc cgcgctctcg ctccggcggc ccaaagtaac ttcgggagcc 120 tcggtctccc gctaacttcc ccccgcgggc tcggttgccc ggacccgctc ggctcgagcc 180 cgccgccggc tcgccttccc cgcacgcggc tcctccgtgc cggtgcctcc gaaagtggat 240 gagagagcgc gcggggcgcg cggcggcacg gagcgcggcg gc atg gag cgc ggc 294 Met Glu Arg Gly 1 tgc tgg gcg ccg cgg gct ctc gtc ctg gcc gtg ctg ctg ctg ctg gcg 342 Cys Trp Ala Pro Arg Ala Leu Val Leu Ala Val Leu Leu Leu Leu Ala 5 10 15 20 acg ctg agg gcg cgc gcg gcc acc ggc tac tac ccg cgc ttc tcg cct 390 Thr Leu Arg Ala Arg Ala Ala Thr Gly Tyr Tyr Pro Arg Phe Ser Pro 25 30 35 ttc ttt ttc ctg tgc acc cac cac ggg gag ctg gaa ggg gat ggg gag 438 Phe Phe Phe Leu Cys Thr His His Gly Glu Leu Glu Gly Asp Gly Glu 40 45 50 cag ggc gag gtg ctc att tcc ctg cac att gcg ggc aac ccc acc tac 486 Gln Gly Glu Val Leu Ile Ser Leu His Ile Ala Gly Asn Pro Thr Tyr 55 60 65 tac gta ccg gga cag gaa tac cat gtt aca att tca aca agc acc ttc 534 Tyr Val Pro Gly Gln Glu Tyr His Val Thr Ile Ser Thr Ser Thr Phe 70 75 80 ttt gat ggc ttg ctg gtg acg gga ctc tat acc tcg aca agc atc cag 582 Phe Asp Gly Leu Leu Val Thr Gly Leu Tyr Thr Ser Thr Ser Ile Gln 85 90 95 100 tct tct cag agc att gga ggc tcc agc gcc ttt gga ttc ggg atc atg 630 Ser Ser Gln Ser Ile Gly Gly Ser Ser Ala Phe Gly Phe Gly Ile Met 105 110 115 tcc gac cac cag ttt ggt aac cag ttt atg tgc agt gtg gtg gcc tct 678 Ser Asp His Gln Phe Gly Asn Gln Phe Met Cys Ser Val Val Ala Ser 120 125 130 cat gtg agt cac ctg cct aca acc aac ctc agc ttt gtc tgg att gcc 726 His Val Ser His Leu Pro Thr Thr Asn Leu Ser Phe Val Trp Ile Ala 135 140 145 cca cca gct ggc aca ggc tgt gtg aat ttc atg gct act gca aca cat 774 Pro Pro Ala Gly Thr Gly Cys Val Asn Phe Met Ala Thr Ala Thr His 150 155 160 agg ggc cag gtg att ttc aaa gac gca ctg gcc cag cag ctg tgt gaa 822 Arg Gly Gln Val Ile Phe Lys Asp Ala Leu Ala Gln Gln Leu Cys Glu 165 170 175 180 caa gga gct ccc aca gag gcc act gct tac tcg cac ctt gct gaa ata 870 Gln Gly Ala Pro Thr Glu Ala Thr Ala Tyr Ser His Leu Ala Glu Ile 185 190 195 cac agt gac agt gtg atc cta cga gat gac ttt gac tcc tac cag caa 918 His Ser Asp Ser Val Ile Leu Arg Asp Asp Phe Asp Ser Tyr Gln Gln 200 205 210 ctg gaa ttg aac ccc aac ata tgg gtt gaa tgc agc aac tgt gag atg 966 Leu Glu Leu Asn Pro Asn Ile Trp Val Glu Cys Ser Asn Cys Glu Met 215 220 225 gga gag cag tgt ggc acc atc atg cat ggc aat gct gtc acc ttc tgt 1014 Gly Glu Gln Cys Gly Thr Ile Met His Gly Asn Ala Val Thr Phe Cys 230 235 240 gag ccg tac ggc cct cga gag ctg acc acc aca tgc ctg aac aca aca 1062 Glu Pro Tyr Gly Pro Arg Glu Leu Thr Thr Thr Cys Leu Asn Thr Thr 245 250 255 260 aca gca tct gtc ctc cag ttt tcc att ggg tca gga tca tgt cga ttt 1110 Thr Ala Ser Val Leu Gln Phe Ser Ile Gly Ser Gly Ser Cys Arg Phe 265 270 275 agt tac tct gac ccc agc atc act gtg tca tac gcc aag aac aat acc 1158 Ser Tyr Ser Asp Pro Ser Ile Thr Val Ser Tyr Ala Lys Asn Asn Thr 280 285 290 gct gat tgg att cag ctg gag aaa att aga gcc cct tcc aat gtg agc 1206 Ala Asp Trp Ile Gln Leu Glu Lys Ile Arg Ala Pro Ser Asn Val Ser 295 300 305 aca gtc atc cac atc ctg tac ctc ccc gag gaa gcc aaa ggg gag agc 1254 Thr Val Ile His Ile Leu Tyr Leu Pro Glu Glu Ala Lys Gly Glu Ser 310 315 320 gtg cag ttc cag tgg aaa cag gac agc ctg cga gtg ggt gag gtg tat 1302 Val Gln Phe Gln Trp Lys Gln Asp Ser Leu Arg Val Gly Glu Val Tyr 325 330 335 340 gag gcc tgc tgg gcc ctg gat aac atc ctg gtc atc aat tca gcc cac 1350 Glu Ala Cys Trp Ala Leu Asp Asn Ile Leu Val Ile Asn Ser Ala His 345 350 355 aga gaa gtc gtt ctg gag gac aac ctc gac ccg gtc gac acg ggc aac 1398 Arg Glu Val Val Leu Glu Asp Asn Leu Asp Pro Val Asp Thr Gly Asn 360 365 370 tgg ctc ttc ttc cct gga gca acg gtc aag cat agc tgt cag tca gat 1446 Trp Leu Phe Phe Pro Gly Ala Thr Val Lys His Ser Cys Gln Ser Asp 375 380 385 ggg aac tcc att tat ttc cat gga aat gaa ggc agc gag ttc aat ttt 1494 Gly Asn Ser Ile Tyr Phe His Gly Asn Glu Gly Ser Glu Phe Asn Phe 390 395 400 gcc acc acc cgg gat gta gat ctt tct aca gag gat att caa gag cag 1542 Ala Thr Thr Arg Asp Val Asp Leu Ser Thr Glu Asp Ile Gln Glu Gln 405 410 415 420 tgg tca gaa gaa ttt gag agc cag ccc aca gga tgg gat atc ttg gga 1590 Trp Ser Glu Glu Phe Glu Ser Gln Pro Thr Gly Trp Asp Ile Leu Gly 425 430 435 gca gta gtt ggt gca gac tgt gga acc gta gaa tca gga cta tca ctg 1638 Ala Val Val Gly Ala Asp Cys Gly Thr Val Glu Ser Gly Leu Ser Leu 440 445 450 gtg ttc ctc aaa gat gga gag agg aag ctt tgc acc ccc tac atg gat 1686 Val Phe Leu Lys Asp Gly Glu Arg Lys Leu Cys Thr Pro Tyr Met Asp 455 460 465 aca act ggt tat ggc aac ctg agg ttc tac ttc gtt atg gga gga atc 1734 Thr Thr Gly Tyr Gly Asn Leu Arg Phe Tyr Phe Val Met Gly Gly Ile 470 475 480 tgt gac cct gga gtc tct cat gaa aac gat atc atc tta tat gca aag 1782 Cys Asp Pro Gly Val Ser His Glu Asn Asp Ile Ile Leu Tyr Ala Lys 485 490 495 500 att gaa gga aga aaa gaa cac att gca ctg gac act ctt acc tat tct 1830 Ile Glu Gly Arg Lys Glu His Ile Ala Leu Asp Thr Leu Thr Tyr Ser 505 510 515 tcc tat aag gtt ccg tct ttg gtt tct gtg gtc atc aac cct gaa ctt 1878 Ser Tyr Lys Val Pro Ser Leu Val Ser Val Val Ile Asn Pro Glu Leu 520 525 530 cag aca cct gcc acc aaa ttt tgt ctc agg caa aag agc cac caa ggg 1926 Gln Thr Pro Ala Thr Lys Phe Cys Leu Arg Gln Lys Ser His Gln Gly 535 540 545 tat aat cgg aat gtc tgg gct gtg gac ttc ttc cat gtg ctg ccc gtt 1974 Tyr Asn Arg Asn Val Trp Ala Val Asp Phe Phe His Val Leu Pro Val 550 555 560 ctc cct tca aca atg tct cac atg atc cag ttt tct att aat ttg gga 2022 Leu Pro Ser Thr Met Ser His Met Ile Gln Phe Ser Ile Asn Leu Gly 565 570 575 580 tgc ggc aca cac cag cct ggg aac agg tga gaagcatgcc gagtgtccta 2072 Cys Gly Thr His Gln Pro Gly Asn Arg 585 acatggtagg aaataaacac atgcactgga ccattgaagt aagtttgtca gtaggatttt 2132 tggatgggat tttaacaaaa tatccattaa gaaaatacag attcctactc cctccctaaa 2192 agagttcttt ggttaataaa tagaagggat gtgactgggt agatttttag gttagaatag 2252 tttcattcag ggagcttgat acaagttatc agaggtgttc accatgctgt gtggcagcat 2312 cccccgttct aacagattgc tgggtgaaga tgactgaaga caagattggc ttctgttggc 2372 tggtgacccc ttataatagg tatggaagtc aattagcact tcaagggcta tgacttctct 2432 gctcctcttg cataagtgtt gctcccatcc tctgtaaaga actttgctga cctcacattc 2492 acaggatgaa gtgacagtgt gagacatggt aattgcctag ctatctatca aattcaagag 2552 cacaaaccca gtttactgtg tattgtcctt cagacgtagc ttttatggca gtaatccaat 2612 ggcttgccct ctgaaggctg gtcaggcttc agtgagagat gacacattta gtaaaggtct 2672 tagagaaatc ccacattcat cgactcattc aaggtattta gctagaaata aaaagaatca 2732 aaaaaataaa tta 2745 4 589 PRT Mus musculus 4 Met Glu Arg Gly Cys Trp Ala Pro Arg Ala Leu Val Leu Ala Val Leu 1 5 10 15 Leu Leu Leu Ala Thr Leu Arg Ala Arg Ala Ala Thr Gly Tyr Tyr Pro 20 25 30 Arg Phe Ser Pro Phe Phe Phe Leu Cys Thr His His Gly Glu Leu Glu 35 40 45 Gly Asp Gly Glu Gln Gly Glu Val Leu Ile Ser Leu His Ile Ala Gly 50 55 60 Asn Pro Thr Tyr Tyr Val Pro Gly Gln Glu Tyr His Val Thr Ile Ser 65 70 75 80 Thr Ser Thr Phe Phe Asp Gly Leu Leu Val Thr Gly Leu Tyr Thr Ser 85 90 95 Thr Ser Ile Gln Ser Ser Gln Ser Ile Gly Gly Ser Ser Ala Phe Gly 100 105 110 Phe Gly Ile Met Ser Asp His Gln Phe Gly Asn Gln Phe Met Cys Ser 115 120 125 Val Val Ala Ser His Val Ser His Leu Pro Thr Thr Asn Leu Ser Phe 130 135 140 Val Trp Ile Ala Pro Pro Ala Gly Thr Gly Cys Val Asn Phe Met Ala 145 150 155 160 Thr Ala Thr His Arg Gly Gln Val Ile Phe Lys Asp Ala Leu Ala Gln 165 170 175 Gln Leu Cys Glu Gln Gly Ala Pro Thr Glu Ala Thr Ala Tyr Ser His 180 185 190 Leu Ala Glu Ile His Ser Asp Ser Val Ile Leu Arg Asp Asp Phe Asp 195 200 205 Ser Tyr Gln Gln Leu Glu Leu Asn Pro Asn Ile Trp Val Glu Cys Ser 210 215 220 Asn Cys Glu Met Gly Glu Gln Cys Gly Thr Ile Met His Gly Asn Ala 225 230 235 240 Val Thr Phe Cys Glu Pro Tyr Gly Pro Arg Glu Leu Thr Thr Thr Cys 245 250 255 Leu Asn Thr Thr Thr Ala Ser Val Leu Gln Phe Ser Ile Gly Ser Gly 260 265 270 Ser Cys Arg Phe Ser Tyr Ser Asp Pro Ser Ile Thr Val Ser Tyr Ala 275 280 285 Lys Asn Asn Thr Ala Asp Trp Ile Gln Leu Glu Lys Ile Arg Ala Pro 290 295 300 Ser Asn Val Ser Thr Val Ile His Ile Leu Tyr Leu Pro Glu Glu Ala 305 310 315 320 Lys Gly Glu Ser Val Gln Phe Gln Trp Lys Gln Asp Ser Leu Arg Val 325 330 335 Gly Glu Val Tyr Glu Ala Cys Trp Ala Leu Asp Asn Ile Leu Val Ile 340 345 350 Asn Ser Ala His Arg Glu Val Val Leu Glu Asp Asn Leu Asp Pro Val 355 360 365 Asp Thr Gly Asn Trp Leu Phe Phe Pro Gly Ala Thr Val Lys His Ser 370 375 380 Cys Gln Ser Asp Gly Asn Ser Ile Tyr Phe His Gly Asn Glu Gly Ser 385 390 395 400 Glu Phe Asn Phe Ala Thr Thr Arg Asp Val Asp Leu Ser Thr Glu Asp 405 410 415 Ile Gln Glu Gln Trp Ser Glu Glu Phe Glu Ser Gln Pro Thr Gly Trp 420 425 430 Asp Ile Leu Gly Ala Val Val Gly Ala Asp Cys Gly Thr Val Glu Ser 435 440 445 Gly Leu Ser Leu Val Phe Leu Lys Asp Gly Glu Arg Lys Leu Cys Thr 450 455 460 Pro Tyr Met Asp Thr Thr Gly Tyr Gly Asn Leu Arg Phe Tyr Phe Val 465 470 475 480 Met Gly Gly Ile Cys Asp Pro Gly Val Ser His Glu Asn Asp Ile Ile 485 490 495 Leu Tyr Ala Lys Ile Glu Gly Arg Lys Glu His Ile Ala Leu Asp Thr 500 505 510 Leu Thr Tyr Ser Ser Tyr Lys Val Pro Ser Leu Val Ser Val Val Ile 515 520 525 Asn Pro Glu Leu Gln Thr Pro Ala Thr Lys Phe Cys Leu Arg Gln Lys 530 535 540 Ser His Gln Gly Tyr Asn Arg Asn Val Trp Ala Val Asp Phe Phe His 545 550 555 560 Val Leu Pro Val Leu Pro Ser Thr Met Ser His Met Ile Gln Phe Ser 565 570 575 Ile Asn Leu Gly Cys Gly Thr His Gln Pro Gly Asn Arg 580 585 5 22 DNA Artificial Sequence Description of Artificial Sequencesynthetic DNA 5 arttyggnaa ycarttyatg tg 22 6 16 DNA Artificial Sequence Description of Artificial Sequencesynthetic DNA 6 tgytccccat ycartt 16 7 20 DNA Artificial Sequence Description of Artificial Sequencesynthetic DNA 7 atgtcctcac tggaaagatc 20 8 20 DNA Artificial Sequence Description of Artificial Sequencesynthetic DNA 8 cagcaacaca taggggacaa 20 9 51 DNA Artificial Sequence Description of Artificial Sequencesynthetic DNA 9 ggccacgcgt cgactagtac gaattcatct atagcttttt tttttttttt t 51 10 35 DNA Artificial Sequence Description of Artificial Sequencesynthetic DNA 10 cagtgtcgtt gcttcccacg tgagtcatct tccca 35 11 35 DNA Artificial Sequence Description of Artificial Sequencesynthetic DNA 11 cgacaggtac aggatgtgtc aacttcatgg ccaca 35 12 20 DNA Artificial Sequence Description of Artificial Sequencesynthetic DNA 12 tcccacaaca aacctaagtt 20 13 20 DNA Artificial Sequence Description of Artificial Sequencesynthetic DNA 13 atgtcctcac tggaaagatc 20 14 24 DNA Artificial Sequence Description of Artificial Sequencesynthetic DNA 14 cgggataaca ttcagggtat cact 24 15 24 DNA Artificial Sequence Description of Artificial Sequencesynthetic DNA 15 atccatggcg gtaactgtct tcct 24 16 26 DNA Artificial Sequence Description of Artificial Sequencesynthetic DNA 16 gtcctgatct acaaacacct gctact 26 17 22 DNA Artificial Sequence Description of Artificial Sequencesynthetic DNA 17 aggtagcaca tggacaaaat cc 22 18 26 DNA Artificial Sequence Description of Artificial Sequencesynthetic DNA 18 ctgaagcaaa ccagtcaccg tggtca 26 19 25 DNA Artificial Sequence Description of Artificial Sequencesynthetic DNA 19 tagtgagtgt gacaatcaga agtga 25 20 21 DNA Artificial Sequence Description of Artificial Sequencesynthetic DNA 20 ggccctttct ggataagaat c 21 21 27 DNA Artificial Sequence Description of Artificial Sequencesynthetic DNA 21 tcaaccattt gctcatacag atgcaca 27 22 20 DNA Artificial Sequence Description of Artificial Sequencesynthetic DNA 22 cctccaagtc tgcctttatg 20 23 20 DNA Artificial Sequence Description of Artificial Sequencesynthetic DNA 23 gcggacaaca atatgcaagg 20 24 20 DNA Artificial Sequence Description of Artificial Sequencesynthetic DNA 24 gcggacaaca atatgcaagg 20 25 20 DNA Artificial Sequence Description of Artificial Sequencesynthetic DNA 25 ggttgttgac aaactggtcc 20 26 20 DNA Artificial Sequence Description of Artificial Sequencesynthetic DNA 26 cgcgtcgact agtacgaatt 20 27 20 DNA Artificial Sequence Description of Artificial Sequencesynthetic DNA 27 ctgattggat tcagctggag 20 28 20 DNA Artificial Sequence Description of Artificial Sequencesynthetic DNA 28 attcagccca cagagaagtc 20 

What is claimed is:
 1. A truncated Reelin protein comprising an F-spondin domain and a CR-50 recognition site of a Reelin protein but containing no repeat site.
 2. The truncated Reelin protein of claim 1 which is derived from Xenopus or mice.
 3. The truncated Reelin protein of claim 2 which is either one of the following proteins (a) or (b): (a) a protein consisting of an amino acid sequence represented by SEQ ID NO: 2, or (b) a protein consisting of an amino acid sequence differing from the amino acid sequence of SEQ ID NO: 2 by deletion, substitution, or addition of one or more amino acids, and having Reelin protein activity.
 4. The truncated Reelin protein of claim 2 which is either one of the following proteins (a) or (b): (a) a protein consisting of an amino acid sequence represented by SEQ ID NO: 4, or (b) a protein consisting of an amino acid sequence differing from the amino acid sequence of SEQ ID NO: 4 by deletion, substitution, or addition of one or more amino acids, and having Reelin protein activity.
 5. A DNA encoding a truncated Reelin protein comprising an F-spondin domain and a CR-50 recognition site of a Reelin protein but containing no repeat site.
 6. The DNA of claim 5 which is derived from Xenopus or mice.
 7. The DNA of claim 6 encoding either one of the following truncated Reelin proteins (a) or (b): (a) a protein consisting of an amino acid sequence represented by SEQ ID NO: 2, or (b) a protein consisting of an amino acid sequence differing from the amino acid sequence of SEQ ID NO: 2 by deletion, substitution, or addition of one or more amino acids, and having Reelin protein activity.
 8. The DNA of claim 7, which is any one of the following DNAs (a) to (c): (a) a DNA having a nucleotide sequence represented by SEQ ID NO: 1, (b) a DNA hybridizing to a nucleic acid probe which comprises a sequence of 1456th to 2273rd nucleotide in the nucleotide sequence of SEQ ID NO: 1 under stringent conditions, and encoding a protein with Reelin protein activity, or (c) a DNA having a nucleotide sequence which is a degenerate sequence of that of the DNA (a) or (b).
 9. The DNA of claim 6 encoding a truncated Reelin protein which is either one of the following proteins (a) or (b): (a) a protein consisting of an amino acid sequence represented by SEQ ID NO: 4, or (b) a protein consisting of an amino acid sequence differing from the amino acid sequence of SEQ ID NO: 4 by deletion, substitution, or addition of one or more amino acids, and having Reelin protein activity.
 10. The DNA of claim 9 which is any one of the following DNAs (a) to (c): (a) a DNA having a nucleotide sequence represented by SEQ ID NO: 3, (b) a DNA hybridizing to a nucleic acid probe which comprises a sequence of 2053rd to 2758th nucleotide in the nucleotide sequence of SEQ ID NO: 3, and encoding a protein with Reelin protein activity, or (c) a DNA having a nucleotide sequence which is a degenerate sequence of that of the DNA (a) or (b). 